Integrated circuit technology has revolutionized various fields, including computers, control systems, telecommunications, and imaging. In the field of imaging, the charge coupled device (CCD) has been made popular by its performance characteristics. Nevertheless, the solid state CCD integrated circuits needed for imaging are relatively difficult to manufacture, and therefore are expensive. In addition, because of the differing processes involved in the manufacture of the CCD integrated circuits relative to MOS integrated circuits, the signal processing portion of the imaging sensor has typically been located on a separate integrated chip. Thus a CCD imaging device includes at least two integrated circuits: one for the CCD sensor and one for the signal processing logic.
Another class of image sensors is the CMOS active pixel sensor. As noted in U.S. Pat. No. 5,625,210 to Lee et al. (“the '210 patent”), an active pixel sensor refers to an electronic image sensor with active devices, such as transistors, that are associated with each pixel. The active pixel sensor has the advantage of being able to incorporate both signal processing and sensing circuitry within the same integrated circuit because of the CMOS manufacturing techniques.
Because of the advances in image sensor technology, image sensors are now commonplace and are used in small form factor applications, such as personal digital assistants (PDAs) and cell phones. As the size of the image sensor and associated lens decreases, it has been found that increased aberration occurs. Aberration results in undesirable effects, such as shading, “dark corners”, color differences, “reddishness”, and vignetting.
FIG. 1 shows one approach for attempting to correct some of the problems mentioned above. FIG. 1 shows lens 102, a sensor array 104 associated with an image sensor module (not shown), Bayer RGB data 106, a lens correction process 108, an RGB data output 110, image processing 112, and image processed YUV/RGB data 114. As shown in FIG. 1, the lens correction processing is performed on the raw RBG data output 110. Such an approach facilitates easy color control associated with control of automatic white balance 112a (AWB), color matrix 112b, color gain/hue 112c, color gamma correction 112d, YUV conversion 112e, and other image processing 112f. 